Pulverizer



Feb. 15, 1966 w. c. ROGERS 3,235,189

PULVERIZER Filed Oct. 15, 1963 5 Sheets-Sheet 1 WAYNE c. ROGERS IN VEN TOR.

Feb. 15, 1966 w. c. ROGERS PULVERIZER 3 Sheets-Sheet 2 Filed Oct. 15, 1963 INVENTOR.

WAYNE 0 ROGERS BY m Illlilll!!! vlllvlltlllllliltll Feb. 15, 1966 w. c. ROGERS PULVER I ZER 3 Sheets-Sheet 5 Filed Oct. 15, 1963 I'IIlI A WAYNE C. ROGERS INVENTOR BY M I! I, ,llj,

United States Patent 3,235,139 PULVERIZER Wayne C. Rogers, Worcester, Mass, assignor to Riley Stoker Corporation, Worcester, Mass, a corporation of Massachusetts Fiierl Oct. 15, 1963, Ser. No. 316,414 6 Claims. (Cl. 241-488) This invention relates to a pulverizer and, more particularly, to apparatus arranged to comminute solid materials such as coal.

In reducing the size of the solid materials and, more particularly, when pulverizing coal for use as a fuel for burning in suspension in the furnace of the steam generating unit, it is common practice to use the process known as attrition. In the attrition method of grinding materials, the particles are carried in air and are subjected to considerable agitation by the rubbing and smashing of one particle against another. The necessary air flow to accomplish this is brought about by the use of revolving aerodynamic members which, in the case of some larger particles, also have a crushing action. Now, the material arriving at the main comminuting stages of a pulverizer may range in grades from very fine to very coarse. As a matter of fact, the lighter particles are probably sufficiently comminuted so that there is no need for their being in the pulverizer at all, but could be carried directly to the burner. Furthermore, the capacity of the mill is determined by the amount of material in the air carried through it and, if part of this material does not need to be pulverized in the first place, a considerable loss in power and capacity in a pulverizer results because the fine particles do take part in the attrition action. The result is that the mill is not operating at its highest capabilities. These and other difiiculties experienced with the prior art devices have been obviated in a novel manner by the present invention.

It is, therefore, an outstanding object of the invention to provide a pulverizer having a very large comminuting capacity for its size.

Another object of this invention is the provision of a pulverizer which operates at maximum efficiency at all times.

A further object of the present invention is the provision of a pulverizer having an integral classification means which permits fine particles of material to bypass the main comminuting elements of the pulverizer.

It is another object of the instant invention to provide a pulverizer having means for bypassing fine particles around the main comminuting elements.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

The character of the invention, however, may be best understood by reference to one of its structural forms as illustrated by the accompanying drawings in which:

FIG. 1 is a vertical sectional view with portions broken away of a pulverizer embodying the principles of the present invention.

FIG. 2 is a transverse sectional view of the pulverizer taken on the line Il-ll of FIG; 1,

FIG. 3 is a vertical sectional view of the invention taken on the line III--III of FIG. 1,

FIG. 4 is a vertical sectional view with portions broken away of the pulverizer taken on the line IVIV of FIG. 1, and

FIG. 5 is a vertical sectional view of the pulverizer taken on the line V-V of FIG. 1.

In the description which follows, the expressions longitudinal, transverse, radial, and axial refer to the centerline of the main drive shaft of the pulverizer.

Referring first to FIG. 1, wherein are best shown the general features of the invention, the pulverizer, indicated generally by the reference numeral 11), is shown as consisting of a housing 11 through which extends a horizontal shaft 12. The pulverizer is a double pulverizer but, for the purposes of clarity of description, only onehalf of the pulverizer is shown; The end which is shown of the shaft 12 is mounted in a bearing 13 which is fastened externally of the housing 11 on a pedestal 14. The housing 11 is provided with a circular end plate 15 against which the pedestal 14 is fastened. To the outer periphery of the end plate 15 is welded a tubular wall 16 which extends longitudinally as far as a transverse wall 17 (see F168. 2 and 3) which is parallel to and spaced from the end wall 15. The junction of the tubular wall 16 and the transverse wall 17 is joined by a radial connecting wall 18 to another tubular wall 19 which extends coaxially of the shaft 12 and is welded to a transverse wall 21 (see FIG. 4). The outer periphery of the transverse wall 21 is welded to a longitudinally-extending tubular wall 22 which, at its other end, is welded to a transverse wall 23; The diameters of the end wall 15, the transverse wall 17, and the tubular wall 16 are approximately the same and serve to define a crushing chamber 24. The diameter of the tubular wall 12 is somewhat larger than that of the tubular wall 16; furthermore, the tubular wall 19 forms a nain pulverization chamber 25 with the transverse wall 17, the connecting wall 18, and the transverse wall 21. The diameters of the transverse walls 21 and 23 and the axial tubular wall 22 are considerably larger than that of the tubular wall 19 and they serve to define a fan chamber 26.

Mounted on the shaft 12 and locked in place thereon are a crusher rotor 27 residing in the crushing chamber 254, a pulverizing rotor 28 mountedon the shaft in the main pulverization chamber 25, and a fan rotor 29 mounted in the fan chamber 26. The crushing chamber 24 is provided with an entrance opening 31 at the top portion, as is particularly evident in FIG. 3. Mounted on the end wall 15' and on the transverse wall 17 are wear plates 32 and 33, respectively. The crusher rotor 2-7 consists of a central hub 34 keyed to the shaft 12; to the rotor are bolt ed two radially-extending mounting disks 35 and 36. At the outer periphery of the mounting disks are mounted swing hammers 37 of the type shown and described in the patent of Rogers, No. 2,647,695. Lying under the hammers and extending from the end plate 15 to the trans verse wall 17 is a grid 38 having openings adequate to pass a desired size of crushed coal. Extending through the lower part of the transverse Wall1'7 is an opening 39 having inclined plates 41 extending downwardly from its up per edge, these plates having release apertures 42. FIG. 2 shows the manner in which the inclined plates 41 are attached and also shows the access door 46 associated with that section of the pulverizer. As is evident in FIG. 3, the crushing chamber 24' is provided with a tramp metal pocket 43 and an adjustable peripheral crusher plate 4 1. The lower edge of the opening 39 is provided with protective plates 45'.

The pulverizing rotor 23 consists of a hub #17 keyed to the shaft 12 and separated from the hub 34 by a sleeve 48. Bolted to the hub is a disk-like mounting plate 49 on the upstream side of which is mounted a series of wearplates 51 and on the downstream side of which is mounted a series of wear-plates 52. Extending from the plate 49 and held by the wear-plates 51 are a series of carbide-covered pegs 53 which extend longitudinally toward the transverse wall 17. Extending from the other side of the pulverizing rotor 28 and held by the wearplates 52 are a series of carbide-covered pegs 54-. Extending around the inner surface of the tubular wall 19 are a series of peripheral liners 55 which are not only bolted in place but also further locked in place by a series of wear-plates 56 bolted to the wall 17 below the opening 39. The wear-plates 56 serve in the dual capacity of protecting the plate at the lower edge of the opening 39 as well as holding the peripheral liners in place. These liners are provided with serrations 57 arranged in two rows on either side of the rotor 28.

Extending outwardly from the transverse wall 21 in the vicinity of the pegs 54 of the rotor and arranged concentrically of a circular central circular discharge opening 58 are a series of abutments 59. These abutments are hollow and are of generally air foil cross-section, as is best evident in FIG. 4. The abutments are generally elongated with pointed ends and extend in such a way that their median lines are tangential to an imaginary circle of approximately the same diameter as the outlet opening 58. The air foil shape of the abutments results in the defining of nozzle- 01' venturi-shaped passages 61 betv een each adjacent pair. The abutments terminate about halfway between the wall 21 and the rotor 28; over their ends is fastened an annular plate 62, on the rotor side of which are mounted a cover plate 63 on which are mounted fixed pegs 64 protected by squares of tungsten carbide. These pegs are coextensive for a considerable portion of their length with the pegs 54, but reside in a coaxial row located somewhat inwardly of the row of pegs 54. It is interesting to note that each of the pegs 64 is mounted on a bolt 65 extending through the plate 62 to the wall 21, the bolt passing through the hollow center of an abutment 59.

Located around the outer periphery of the row of abutments 59 are director plates 66 having scoop-shaped surfaces for reversal of air flow from axial to radial. As is evident in FIG. 1, these director plates 66 overlie end portions of the peripheral liners 55. The inner periphery of the plate 62 (overlying the abutments 59) is provided with a tubular ring 67 which is directed axially toward the rotor 28 and which is provided with a series of apertures 68. Extending inwardly from the edge of the ring 67 which is closest to the rotor 28 is a radial annular plate 69 whose inner edge terminates close to the hub 47, but which is spaced from and parallel to the outer radial surface of the wear-plates 52. Mounted on the transverse wall 21 around the aperture 58 is a hollow ring 71 extending around the inner periphery of the circle of abutments 59 and having an outwardly-directed conical surface 72 which extends inwardly and toward the rotor 28 at an angle of approximately 45. The hollow ring 71 also has a tubular wall 73 which extends longitudinally through the outlet opening 58 in the wall 21 and extends longitudinally well into the fan chamber 26.

Mounted on the surface of the hollow ring 71 is a ring 74 of L-shaped cross-section having a radiallydirected flange 75 and a longitudinally directed tubular portion 76. The tubular portion 76 slides smoothly along the outer surface of the tubular wall 73 of the hollow ring 71. The upper part of the ring 74 is pro vided with a handle 77 having a slim downstream stem and a broad upstream portion which embraces the ring 74 and is bolted to it. The ring 74 can be rotated slidably over the surface of the hollow ring 71 by pushing on the handle 77 and a U-shaped bolt member 78 limits the peripheral movement of this handle. Spaced around the tubular wall 73 of the hollow ring 71 are several cap head screws 79 which reside in inclined slots 31 formed in the tubular portion 76 of the ring 74, so that peripheral movement of the handle 77 causes axial or longitudinal movement of the ring 74 as well as rotary.

The ends of the abutments 59 press against an annular plate 82 which lies against the surface of the transverse wall 21 and is connected to it by means of bolts 83. The bolts 65 which hold the peg 64 in place also serve to clamp the abutments 59, the plates 62, and the plate 82 together into a unitary assembly. The inner periphery of the plate 82 slides in a recess 84 formed in the outer periphery of the hollow ring 71, while the outer periphery of the annular plate 82 resides in a similar recess 85 formed in the inner edge of the director plates 66. This means that the entire assemblage defining the passages 61, i.e., the annular plate 32, the abutments 59, the annular plates 62, the Wear-plates 63, and the pegs 64 all are capable of rotation around the shaft 12 when the bolts 83 have been removed, this being necessary to permit access since only the top of the housing 11 is removable from the pulverizer once the pulverizer has been installed.

In the fan chamber 26 (referring to FIGS. 1 and 5), the fan rotor 29 is shown as consisting of a hub 86 which is keyed to the shaft 12 and to which is bolted a mounting disk 87, on the face of which are mounted fan blades 83. As is evident in FIG. 5, the tubular wall 22 is scrollshaped and is provided in its inner surface with peripheral liners 89. On the outside portion is mounted a discharge fitting 91 adapted to be connected to conduits leading to the burners of a steam generating unit or the like. The fitting is curved in the usual way and is provided on the outer concave surface of the curve with director pegs 92 which serve to break up the tendency for the flow of fuel and air to be segregated along this curve and to distribute the fuel more evenly throughout the fitting and into the conduit.

The operation of the apparatus will now be readily understood in View of the above description. Assuming that coal is the material which is to be pulverized, the fuel is introduced by a feeder (not shown) into the pulverizer through the entrance opening 31 into the crushing chamber 24. The coal is subjected in the crushing chamber to action by the hammers 37 and, eventually, is reduced to a size sufficient to permit it to pass through the grid 38. Any tramp iron is thrown peripherally into the tramp iron pocket 43 where it may be removed from time to time. The larger particles of coal are smashed against the crusher plate 44 under the impetus of the hammers and of centrifugal force. In the crushing chamber the coal is also mixed with air which may be preheated to promote drying of the coal. The coal-and-air mixture flows through the grid 38 and through the opening 39 in the transverse wall 17. Because the opening 39 is raised from the bottom surface of the tubular wall 16, only those particles which are capable of being carried by the air flow are able to go through the opening 39. Wearing of the plates 17 is prevented by the provision of wear plates 45 and 56 embracing the lower lip of the opening. The fuel and air strike the inclined plates 41 and are directed outwardly and downwardly into the pulverizing chamber 25. Fine particles and air are permitted to pass through the openings 42. The rotation of the shaft 12. and of the crushing rotor 27, the pulverizing rotor 28, and the fan rotor 29 bring about the comminuting action. It should be noted that the main flow of air through the pulverizer is caused by the rotation of the fan rotor. However, the pegs 53 on the pulverizing rotor have a major function in promoting the flow of air outwardly of the rotor 23 to carry the fuel in the proper direction; the fuel is directed to the outer periphery of the rotor, strikes the peripheral liners 55, and is further comminuted by striking the serrations 57 formed in the surface thereof. The fuel-air suspension now flows spirally around the outer periphery of the rotor 28 and enters the portion of the pulverizing chamber on the other side of the rotor. Most of the air-and-fuel mixture continues spirally and eventually strikes the director plates 66 where the tangential and longitudinal movement and the kinetic energy is directed radially inwardly. The mixture enters the passages 61 between the abutments 59. From there they leave the inner end of the passages 61 and are directed longitudinally rearwardly (in the upstream dire-c tion) by the conical surface 72 of the hollow ring '71. Eventually, the fan rotor 29 sucks the mixture of air and fine particles around the hollow ring 71 and through the opening 58 and discharges it from the pulverizer, through the fitting 91. As a matter of fact, most "of the air and those fine particles belowfa predetermined classification will do "this immediately. The "heavier particles, however, as they-leave the passage 61-'a"n'd "s'lide inwardly and rearwardly longitudinally along the conical surface 72 are subjected first of all, to the flow "of air promoted by the fan blades 88 and, secondly, by the centrifugal force which has a tendency to throw them radially outwardly instead of permitting -them to flow radially inwardly to leave through the "opening 58. These heavy particles (over a certain size classification) are afiectedto'a greater extent by centrifugal force and, therefore, move "radially outwardly through the apertures "68 in the tubular ring 67. They then 'flow radially outwardly between the pegs 54 and 64 where they are subjected to a comminuting action in the usual way. The pegs 54 and 64 cause eddy currents, turbulence, and high air speeds which rub the particles against "one another to produce'the attrition action and to comfninute the particles. They continu'eoutwardly of the row of pegs and are entrained in the flow of gas and fuel 'which has just arrived in a spiral direction from around the "outer periphery of the rotor 28. They immediately pass into thepassages "61 and so, if they are sufficiently fine, will goout through the opening '58; if they havestill not been reduced 'sufficiently, they will make another pass'through the apertures 68 and through the pegs 1 and 64*again.

Now, it is well known that the'capa'city of 'anattritiontype pulverizer is limited by the number of pegs which can be provided and the size of the "'mill which restricts the flow of air and fuel to a certain amo'unt,just as any conduit does. That is to say, greater pulverization can be obtained by speeding up themill or in-creasingtheair flow, but this comes about only after a non-proportionate increase of power. In the present device, it'willbe "seen that the major pulverizing elements, ie, the pegs 54 and 64, are required to 'pul-v'erize -or "comminute only the large particles of fuel. T hereis no unnecessary flow of air and hue pulverized fuel between these elements, 'sothat power is not consumed in further freducing coal which has been sufiiciently pulverized already, nor in causing flow of fuel which is sufficiently fine anyway. Basically, then, this pulverizer permits the fine particles to bypass the major pulverizing surfaces but continues to frecirculate the heavier particles until they have been "reduced sufiiciently in size to satisfy the pre-determined specifications for fineness of pulverization.

Now, in order 'to adjust the cut-off point, that is to say, to determine which particles shall be permitted to pass immediately to discharge and which are to be caused to go through the piilverizing elements, an adjustmentis necessary. For this purpose, it is possible, by opening the top half of the pulverizer, to actuate the handle 77, to cause a rotation of the ring 74. When the ring 74 is rotated, the inclined slots 81 cooperate with the'bo1ts'7'9 to cause the rin-gto fnove longitudinally one way or' another. In FIG. 1, the ring is shown in its extreme open position. In another position it will extend outwardly toward the annular plate 69 and reduce the gap and increase the velocity through which all fluid air must pass on its way to the opening 58. Reducing the size of this annular inward passage will cause fewer particles to be thrown outwardly by centrifugal force, so that somewhat larger particles will be permitted to pass immediately to discharge. This provides a range over which the output fineness may be varied as desired.

Referring to FIG. 4, it can be seen that the director plates 66 are so mounted that a longitudinal surface 93 is located at the leading edge of each of the abutments 59. The surface slopes downwardly toward these longitudinal surfaces at all times to provide a sawtooth arrangement which is also curved to direct the fuel and air into the passages 61. As is evident in the drawing, the air flow shape of the abutments 59 causes the passages 61 to -resemble venturis or nozzles so that the air-and-fuel velocity leaving each of the passages 61 is at a relatively 'high value. The passages are arranged at 'a substantial angle to the radial direction, so that the air-and-fue'l flow from the passages is tangential to an imaginary circle concentric with the shaft and located intermediate the shaft and the outer periphery of the rotor. The magnitude of this velocity and the angle of the passages in a radial direction are purposely designed to produce an inwardlydirected vortex fiow in the adjustable gap adjacent the ring 75. Vortex flow is characterized by both tangential and radial velocity components (V and V Material particles followingthe vortex flow are thussubject to two opposing forces; -i. e., 1) an outwardly-directed centrifugal force proportional to Vi /"r, where r is the radius of the particle path, and the cube of the particle diameter, and (52) an inwardly-directedradial drag force proportional to Vr and the particle diameter in "the range'of particle sizes with which we are concerned.

From the above it will be seen that, by a choice of design, particles of a particular size traveling in the vortex flow region will be subjected to equal and opposite radially-directed forces and will tend to rotate in a circle. For particles larger than the selected size, centrifugal force will exceed the inward radial drag force and the particle will spiral outwards into the grinding elements 64- and '54 for further size reduction. Conversely, for particles smaller than the selected diameter, inwardlydirected radial drag force will exc'eedthe centrifugal force acting on the particle, and the particle will spiral inwards towardthe discharge opening 58. Particles of the selected size on which forces are balanced will eventually either go out orin becauseof turbulence in the flow through the gap.

Variation of the gap 'width by adjustment of the ring 74 aflects only the radial velocity component in the gap,

thus changing'the relation-between centrifugal drag forces and affording a range orc'hoice of particle sizes discharged through the opening 58. The larger outward-spiralling particles eventually pass into the grinding zone through apertures 68. In the passage between plate 63 and the rotor element it is necessary and desirable to have either rotation of the conveying medium only, or rotation plus a radially outward component of flow of very lowmagnitude. This is accomplishedby properly selecting the open area of apertures 68 so as to permit passageof the dense large particlestr'e'am but, at'the same time, restricting to 'low values the re'c'irculatingflow of th'e conveying medium and fine dust with attendant energy losses in the grinding zone. Furthermorqthe design of rotor and channel components must be'chosen so as to avoid radially inward flow throughthe grinding zone.

It is obvious that minor changes "may be made in the form and construction of the invention without departing from the material spirit thereof. It is not, however, desired toconfine the invention 'to the-exact form herein "shown a nddescribed,'butit is'desired to include all such as properly come within the scope claimed.

The invention having been thus described, what is claimed as new and desired to secure by Letters Patent 1s:

1. A pulverizer, comprising (a) a housing,

(b) a shaft extending through the housing,

(0) bearings associated with the housing for mounting the shaft for rotation,

(d) a rotor in the form of a disc mounted on the shaft and extending laterally from the shaft in a generally transverse plane, the housing extending around the rotor to form an annular space therearound,

(e) movable pegs extending longitudinally of the shaft from one side of the rotor and movable therewith,

(f) stationary pegs extending longitudinally of the shaft from the housing toward the rotor adjacent the movable pegs,

(g) a series of enclosed passages extending radially from the annular space at the outward side of the movable and stationary pegs to the space at the inward side of the said pegs, the housing being pro- (e) movable pegs extending longitudinally of the shaft from one side of the rotor and movable therewith, (f) stationary pegs extending longitudinally of the shaft 8 from the housing toward the rotor adjacent the movable pegs, (g) a series of enclosed passages extending radially from the annular space at the outward side of the vided with a radial wall parallel to and spaced from movable and stationary pegs to the space at the the surface of the rotor from which the movable inward side of the said pegs, the inner ends of the pegs extend, a ring-like wall supported by the said passages terminating in a circle which is concentric wall in parallel spaced relation thereto and supportwith the shaft,

ing the stationary pegs, and hollow air foil shaped (h) passage means permitting flow of material from connecting members extending between the two 10 the inner end of the said enclosed passages through above-described walls and serving to define the said the pegs to the outer end of the said enclosed paspassages between them, and ages, and

(h) passage means permitting flow of material from (i) a concentric cut-off ring mounted inwardly of the the inner end of the said enclosed passages through said inner ends, the ring being adjustable longitudithe pegs to the outer end of the said enclosed pasnally of the shaft to regulate the annular space be sages. tween the ring and the rotor.

2. A pulverizer as recited in claim 1, wherein the cen- 5. A pulverizer, comprising terlines of the connecting members and the passages are (a) ahousing, tangential to an imaginary circle intermediate the shaft (b) ashaft extending through the housing, a and the outer periphery of the rotor. 1 (c) bearings associated with the housing for mount- 3. A pulverizer, comprising ing the shaft for rotation, 1

(a). a housing, (d) a rotor in the form of a disc mounted on the shaft (b) a shaft extending through the housing, and extending laterally from the shaft in a gen- (c) bearings associated with the housing for mounterally transverse plane, the housing extending around ing the shaft for a rotation, the rotor to form an annular space therearound,

(d) a rotor in the form of a disc mounted on the shaft (e)movable pegs extending longitudinally of the shaft and extending laterally from the shaft in a generally from one side of the rotor and movable therewith, transverse plane, the housing extending around the (f) stationary pegs extending longitudinally of the rotor to form an annular space therearound, shaft from the housing toward the rotor adjacent the (e) movable pegs extending longitudinally of the shaft movable pegs, 4

from one side of the rotor and movable therewith, (g) a series of enclosed passages extending generally (f) stationary pegs extending longitudinally of the radially from the annular space at the outward side shaft from the housing toward the rotor adjacent the of the movable and stationary pegs to the space at movable pegs, the inward side of the said pegs, the said passages (g) a series of enclosed passages extending radially being directed inwardly and tangentially to an imagfrom the annular space at the outward side of the inary circle located inwardly of the inner ends of the movable and stationary pegs to the space at the insaid passages and concentric to the said shaft, and ward side of the said pegs, and (h) passage means permitting flow of material from (h) passage means permitting flow of material from the inner end of the said enclosed passages through the inner end of the said enclosed passages through the peg to theouter end of the said enclosed passages. the pegs to the outer end of the said enclosed pas- 6. A pulverizer as recited in claim 5, wherein each sages, each passage having a nozzle conformation passage consists of a first portion which is inclined radially to accelerate air flow at the inner discharge end to inwardly and longitudinally away from the rotor, a secfacilitate classification. ond portion which extends substantially radially only,

4. A pulverizer, comprising and a third portion which is inclined inwardly and longi- (a) a housing, tudinally toward the rotor.

(b) a shaft extending through the housing,

(0) bearings associated with the housing for mount- References Cited y the Examiner ing the shaft forhrotation, 0 UNITED STATES; PATENTS d) a rotor in t e form of a disc mounted on the J shaft and extending laterally from the shaft in a 1603520 10/1926 cn'tes et '7 241 56 generally transverse plane, the housing extending 2096274 10/1937 Beach 241 56 around the rotor to form an annular space there- 2699898 1/1955 Rogers 24156 X around, 3,157,366 11/1964 Rogers 241-488 ROBERT c. RIORDON, Primary Examiner. J. SPENCER OVERHOLSER, Examiner, 

5. A PULVERIZER, COMPRISING (A) A HOUSING, (B) A SHAFT EXTENDING THROUGH THE HOUSING, (C) BEARINGS ASSOCIATED WITH THE HOUSING FOR MOUNTING THE SHAFT FOR ROTATION, (D) A ROTOR IN THE FORM OF A DISC MOUNTED ON THE SHAFT AND EXTENDING LATERALLY FROM THE SHAFT IN A GENERALLY TRANSVERSE PLANE, THE HOUSING EXTENDING AROUND THE ROTOR TO FORM AN ANNULAR SPACE THEREAROUND, (E) MOVABLE PEGS EXTENDING LONGITUDINALLY OF THE SHAFT FROM ONE SIDE OF THE ROTOR AND MOVABLE THEREWITH, (F) STATIONARY PEGS EXTENDING LONGITUDINALLY OF THE SHAFT FROM THE HOUSING TOWARD THE ROTOR ADJACENT THE MOVABLE PEGS, (G) A SERIES OF ENCLOSED PASSAGES EXTENDING GENERALLY RADIALLY FROM THE ANNULAR SPACE AT THE OUTWARD SIDE OF THE MOVABLE AND STATIONARY PEGS TO THE SPACE AT THE INWARD SIDE OF THE SAID PEGS, THE SAID PASSAGES BEING DIRECTED INWARDLY AND TANGENTIALLY TO AN IMAGINARY CIRCLE LOCATED INWARDLY OF THE INNER ENDS OF THE SAID PASSAGE AND CONCENTRIC TO THE SAID SHAFT, AND (H) PASSAGE MEANS PERMITTING FLOW OF MATERIAL FROM THE INNER END OF THE SAID ENCLOSED PASSAGES THROUGH THE PEG TO THE OUTER END OF THE SAID ENCLOSED PASSAGES. 